Study type: Medical/biological study (experimental study)

Nocturnal magnetic field exposure: gender-specific effects on heart rate variability and sleep. med./bio.

Published in: Clin Neurophysiol 2000; 111 (11): 1936-1941

Aim of study (acc. to author)

To determine if controlled exposure to magnetic fields alters the heart rate variability and sleep in older (40-60 years) probands.

Background/further details

Healthy men (n=22) and women (n=24) slept in the test room from 23:00 to 07:00 h on two nights spaced over a week. These first two sessions were used to evaluate the effects of nocturnal exposure on cardiac endpoints. Half the subjects selected at random were exposed on the first test night, and then sham exposed on the second night; the remaining subjects participated in the reverse order. One week later, the probands returned for a further two nights to test the sleep parameters.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: intermittent for 8 h (1 h on, 1 h off; during field on: field cycled between on and off in 15 s intervals)

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Polarization
  • circular
Exposure duration intermittent for 8 h (1 h on, 1 h off; during field on: field cycled between on and off in 15 s intervals)
Exposure setup
Exposure source
Chamber each subject slept overnight in a sound-attenuated and air-conditioned exposure test room (a cube about 2.4 m on each side)
Setup Merrit-type horizontal and vertical concentric coil system surrounding the exposure chamber; one axis of the field was phase-shifted 90°
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 28.3 µT - - - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • before exposure
  • during exposure

Main outcome of study (acc. to author)

Regarding the heart rate variability, under exposure conditions, male probands showed a decrease in the power spectrum (respective low frequency) over the entire night compared to sham exposure conditions. No field-related effects were found in women.
Regarding the sleep, exposed women showed a decreased percentage of time in REM sleep compared to sham exposed women. Additionally, the total amount of time the women remained asleep and sleep efficiency was reduced compared to the sham exposed women. No field-related effects were found in men.
The authors conclude that gender-specific effects seen in this study in older volunteers, replicate the results of previous studies with younger men and women (Sastre, 1998; Sait, 1999; Graham, 1996).

Study character:

Study funded by

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